Mid-infrared resonant reaction in confined space driven by vibrational excitation

Photochemical reactions and photosynthesis induced by ultraviolet or visible light excitation have been extensively investigated [1][2][3] .However, driving photochemical transformations via mid-infrared 15 vibrational excitation of specific chemical bonds remains a significant challenge.Herein, we demonstrate that a ~3 μm mid-infrared laser enables the selective excitation of the C-H stretching vibration (υC-H = 3249 cm -1 , λads ≈ 3 μm) of acetylene (C2H2) molecules confined within the channels of a metal-organic framework (MOF), resulting in the formation of hydrogen gas and single-walled 4 Å carbon nanotubes (CNTs).This photochemical process, rather than a thermochemical reaction, is confirmed to be a 20 photochemical reaction, as evidenced by its wavelength selectivity and polarization dependence.Meanwhile, the light intensity dependence of the process indicates that it involves a multiphoton excitation, which is achieved via the prolonged lifetime of excited states due to confinement effects.This study marks